WO2013031028A1 - 内燃機関の排気浄化装置 - Google Patents

内燃機関の排気浄化装置 Download PDF

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Publication number
WO2013031028A1
WO2013031028A1 PCT/JP2011/070086 JP2011070086W WO2013031028A1 WO 2013031028 A1 WO2013031028 A1 WO 2013031028A1 JP 2011070086 W JP2011070086 W JP 2011070086W WO 2013031028 A1 WO2013031028 A1 WO 2013031028A1
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WIPO (PCT)
Prior art keywords
exhaust
hydrocarbon
hydrocarbons
amount
purification catalyst
Prior art date
Application number
PCT/JP2011/070086
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English (en)
French (fr)
Japanese (ja)
Inventor
三樹男 井上
吉田　耕平
悠樹 美才治
Original Assignee
トヨタ自動車株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by トヨタ自動車株式会社 filed Critical トヨタ自動車株式会社
Priority to JP2012504214A priority Critical patent/JP5218698B1/ja
Priority to EP11838998.0A priority patent/EP2589769B1/de
Priority to CN201180004306.9A priority patent/CN103097680B/zh
Priority to US13/510,156 priority patent/US8689546B2/en
Priority to PCT/JP2011/070086 priority patent/WO2013031028A1/ja
Publication of WO2013031028A1 publication Critical patent/WO2013031028A1/ja

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
    • F01N3/033—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters in combination with other devices
    • F01N3/035—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters in combination with other devices with catalytic reactors, e.g. catalysed diesel particulate filters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
    • F01N3/023—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles
    • F01N3/025—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles using fuel burner or by adding fuel to exhaust
    • F01N3/0253—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles using fuel burner or by adding fuel to exhaust adding fuel to exhaust gases
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0814—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents combined with catalytic converters, e.g. NOx absorption/storage reduction catalysts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0821—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents combined with particulate filters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0828—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents characterised by the absorbed or adsorbed substances
    • F01N3/0842—Nitrogen oxides
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F01N3/2006—Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating
    • F01N3/2033—Periodically heating or cooling catalytic reactors, e.g. at cold starting or overheating using a fuel burner or introducing fuel into exhaust duct
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/021—Introducing corrections for particular conditions exterior to the engine
    • F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
    • F02D41/027—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to purge or regenerate the exhaust gas treating apparatus
    • F02D41/0275—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to purge or regenerate the exhaust gas treating apparatus the exhaust gas treating apparatus being a NOx trap or adsorbent
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/021—Introducing corrections for particular conditions exterior to the engine
    • F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
    • F02D41/027—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to purge or regenerate the exhaust gas treating apparatus
    • F02D41/029—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to purge or regenerate the exhaust gas treating apparatus the exhaust gas treating apparatus being a particulate filter
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
    • F02D41/1408—Dithering techniques
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/03—Adding substances to exhaust gases the substance being hydrocarbons, e.g. engine fuel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/08—Exhaust gas treatment apparatus parameters
    • F02D2200/0806—NOx storage amount, i.e. amount of NOx stored on NOx trap
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/021—Introducing corrections for particular conditions exterior to the engine
    • F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
    • F02D41/024—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to increase temperature of the exhaust gas treating apparatus
    • F02D41/025—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to increase temperature of the exhaust gas treating apparatus by changing the composition of the exhaust gas, e.g. for exothermic reaction on exhaust gas treating apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/30—Controlling fuel injection
    • F02D41/38—Controlling fuel injection of the high pressure type
    • F02D41/40—Controlling fuel injection of the high pressure type with means for controlling injection timing or duration
    • F02D41/402—Multiple injections
    • F02D41/405—Multiple injections with post injections
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Definitions

  • the present invention relates to an exhaust purification device for an internal combustion engine.
  • components such as carbon monoxide (CO), unburned fuel (HC), nitrogen oxides (NO x ), or particulate matter (PM) are contained in exhaust gas from internal combustion engines such as diesel engines and gasoline engines. It is included.
  • An exhaust gas purification device is attached to the internal combustion engine to purify these components.
  • As a method for removing nitrogen oxides it is known to dispose a NO X storage catalyst in the engine exhaust passage.
  • a method for removing particulate matter it is known to arrange a particulate filter in the engine exhaust passage.
  • a NO X storage catalyst and a PM filter are provided in an exhaust passage, and a second part for supplying fuel to the PM filter is provided at an intermediate portion between the NO X storage catalyst and the PM filter.
  • An exhaust gas purification system for an internal combustion engine in which a fuel addition valve, a mixer, and an oxidation catalyst are arranged in this order is arranged. At the time of regeneration of the PM filter, it is disclosed that the temperature of the exhaust gas rises due to the fuel supplied from the second fuel addition valve being oxidized in the oxidation catalyst, and the temperature of the PM filter also rises.
  • the temperature of the exhaust near the mixer is set before the fuel addition from the second fuel addition valve. It is disclosed that the fuel added from the second fuel addition valve is raised to a temperature at which the fuel is surely vaporized in the mixer.
  • NO X contained in the exhaust can be purified by the NO X storing catalyst repeating the release and reduction of storage and NO X in the NO X.
  • NO X can be absorbed in the form of nitrate ions inside the NO X absorbent, NO X can be removed from the.
  • NO X absorbed in the interior of the NO X absorbent by making the air-fuel ratio of the exhaust gas the stoichiometric air-fuel ratio or rich, is released from the interior of the absorbent.
  • NO X released from the inside of the absorbent is reduced to nitrogen by a reducing agent such as hydrocarbon contained in the exhaust gas.
  • the particulate matter collected by the particulate filter can be removed by increasing the temperature of the particulate filter.
  • the particulate filter is raised by supplying hydrocarbons such as fuel to a catalyst that is disposed upstream of the particulate filter and capable of oxidizing hydrocarbons such as fuel. The temperature can be done.
  • the present invention includes an exhaust purification catalyst that purifies NO X and an aftertreatment device that raises the temperature when a predetermined state is reached, and obtains a high NO X purification rate even when the exhaust purification catalyst reaches a high temperature. Another object of the present invention is to provide an exhaust purification device for an internal combustion engine that suppresses the passage of hydrocarbons when the temperature of the aftertreatment device is raised.
  • An exhaust gas purification apparatus for an internal combustion engine includes an exhaust gas purification catalyst for reacting NO X contained in exhaust gas with reformed hydrocarbons in an engine exhaust passage, and an exhaust flow surface of the exhaust gas purification catalyst.
  • a noble metal catalyst is supported on the top, and a basic exhaust flow surface portion is formed around the noble metal catalyst.
  • the exhaust purification catalyst has a predetermined concentration of hydrocarbons flowing into the exhaust purification catalyst. When it is vibrated with an amplitude within a range and a period within a predetermined range, it has the property of reducing NO X contained in the exhaust gas, and the oscillation period of the hydrocarbon concentration is longer than the predetermined range. As a result, the storage amount of NO X contained in the exhaust gas is increased.
  • the exhaust purification device is disposed in the engine exhaust passage downstream of the exhaust purification catalyst, and includes an aftertreatment device that raises the temperature when a predetermined state is reached, and exhaust gas is generated by the oxidation heat of hydrocarbons generated in the exhaust purification catalyst.
  • the temperature raising control is performed to raise the temperature and raise the temperature of the post-processing apparatus. In the control for oscillating the concentration of hydrocarbons flowing into the exhaust purification catalyst with an amplitude within a predetermined range and a cycle within a predetermined range, a predetermined total supply amount of hydrocarbons is predetermined.
  • a high purification rate purifying ratio is varied long supply period of hydrocarbons NO X becomes higher than the purification rate of increase range and predetermined NO X increases Have a range.
  • the temperature rise control the total supply amount of hydrocarbons required for the temperature rise of the aftertreatment device is set, and within the high purification rate range, within the end region on the side where the hydrocarbon feed cycle is short, The supply cycle and the supply amount of hydrocarbon per time are set, and the hydrocarbon is supplied at the set hydrocarbon supply cycle and the supply amount of hydrocarbon per time.
  • the specific supply cycle that is the shortest hydrocarbon supply cycle in the high purification rate range and the specific supply amount that is the hydrocarbon supply amount per time corresponding to the specific supply cycle It is preferable to supply hydrocarbons.
  • the operating state of the internal combustion engine is detected at predetermined intervals, and the hydrocarbon supply cycle and the hydrocarbon supply per time are determined based on the detected operating state of the internal combustion engine. It is preferable to set the amount and change the hydrocarbon feed cycle and the amount of hydrocarbon feed per time.
  • the post-processing apparatus includes a particulate filter
  • the temperature raising control can include a control for increasing the temperature in order to oxidize particulate matter deposited on the particulate filter.
  • NO x contained in the exhaust gas and the reformed hydrocarbon react to generate a reducing intermediate containing nitrogen and hydrocarbon, and the hydrocarbon
  • the oscillation period of the concentration of can be the period necessary to continue to produce the reducing intermediate.
  • the noble metal catalyst can be composed of at least one of rhodium Rh and palladium Pd and platinum Pt.
  • the exhaust purification catalyst is formed in the exhaust flow on a surface, comprising a base layer comprising a metal which can donate electrons to an alkali metal or alkaline earth metal or rare earth or NO X, the surface of the basic layer Can form a basic exhaust flow surface portion.
  • an exhaust purification catalyst that purifies NO X and an aftertreatment device that raises the temperature when it reaches a predetermined state are provided, and a high NO X purification rate even when the exhaust purification catalyst becomes high temperature. Further, it is possible to provide an exhaust gas purification apparatus for an internal combustion engine that suppresses the passage of hydrocarbons when the temperature of the aftertreatment device is raised.
  • FIG. 1 is an overall view of a compression ignition type internal combustion engine according to an embodiment.
  • FIG. 2 is a view schematically showing the surface portion of the catalyst carrier.
  • FIG. 3 is a diagram for explaining an oxidation reaction in the exhaust purification catalyst.
  • FIG. 4 is a diagram showing a change in the air-fuel ratio of exhaust flowing into the exhaust purification catalyst in the first NO X purification method.
  • FIG. 5 is a diagram showing the NO X purification rate of the first NO X purification method.
  • 6A and 6B are diagrams for explaining the oxidation-reduction reaction by the exhaust purification catalyst in the first NO X purification method.
  • 7A and 7B are diagrams for explaining the oxidation-reduction reaction by the exhaust purification catalyst in the second NO X purification method.
  • FIG. 1 is an overall view of a compression ignition type internal combustion engine according to an embodiment.
  • FIG. 2 is a view schematically showing the surface portion of the catalyst carrier.
  • FIG. 3 is a diagram for
  • FIG. 8 is a diagram showing a change in the air-fuel ratio of exhaust flowing into the exhaust purification catalyst in the second NO X purification method.
  • FIG. 9 is a diagram showing the NO X purification rate of the second NO X purification method.
  • FIG. 10 is a time chart showing changes in the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst in the first NO X purification method.
  • FIG. 11 is another time chart showing the change in the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst in the first NO X purification method.
  • FIG. 12 is a diagram showing the relationship between the oxidizing power of the exhaust purification catalyst and the required minimum air-fuel ratio X in the first NO X purification method.
  • FIG. 13 is a diagram showing the relationship between the oxygen concentration in the exhaust gas and the amplitude ⁇ H of the hydrocarbon concentration, in which the same NO X purification rate can be obtained in the first NO X purification method.
  • FIG. 14 is a diagram showing the relationship between the hydrocarbon concentration amplitude ⁇ H and the NO X purification rate in the first NO X purification method.
  • FIG. 15 is a diagram showing the relationship between the vibration period ⁇ T of the hydrocarbon concentration and the NO X purification rate in the first NO X purification method.
  • FIG. 16 is a diagram showing changes in the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst, etc., in the second NO X purification method.
  • FIG. 17 is a diagram showing a map of the NO X emission amount NOXA.
  • FIG. 18 is a diagram showing the fuel injection timing in the combustion chamber in the second NO X purification method.
  • FIG. 19 is a diagram showing a map of the hydrocarbon supply amount WR in the second NO X purification method.
  • FIG. 20 is a diagram showing a hydrocarbon injection pattern from a hydrocarbon feed valve, a change in hydrocarbon concentration of exhaust gas flowing into the exhaust purification catalyst, and the like in the first NO X purification method.
  • FIG. 21 is a diagram illustrating a hydrocarbon injection pattern and a change in hydrocarbon concentration when the operating state of the internal combustion engine changes in the first NO X purification method.
  • FIG. 22 is a flowchart of operation control of the first NO X purification method during normal operation.
  • FIG. 23 is a graph illustrating the relationship between the active NO X retention amount of the exhaust purification catalyst and the NO X retention capability speed.
  • FIG. 24 is a flowchart of control for estimating the active NO X retention amount of the exhaust purification catalyst.
  • FIG. 25 is a graph for explaining the relationship between the active NO X retention amount and the hydrocarbon supply amount.
  • FIG. 26 is a graph illustrating the relationship between the hydrocarbon supply cycle and the amount of hydrocarbon supply per time in the temperature rise control according to the embodiment.
  • FIG. 27 is a graph illustrating the relationship between the hydrocarbon supply cycle and the NO x purification rate in the temperature rise control according to the embodiment.
  • FIG. 28 is a flowchart of temperature increase control for regeneration of the particulate filter in the embodiment.
  • FIG. 29 is a map of the amount of one-time supply of hydrocarbons using the engine speed and the fuel injection amount in the combustion chamber as functions.
  • FIG. 30 is a map of the hydrocarbon supply cycle in which the engine speed and the fuel injection amount in the combustion chamber are functions.
  • FIG. 31 is a time chart of an operation example in which the temperature rise control in the embodiment is performed.
  • FIG. 32 is a time chart of another operation example in which the temperature rise control in the embodiment is performed.
  • FIG. 33 is a time chart of still another operation example when the temperature of the particulate filter is raised in the embodiment.
  • FIG. 1 is an overall view of an internal combustion engine in the present embodiment.
  • the internal combustion engine includes an engine body 1.
  • the internal combustion engine also includes an exhaust purification device that purifies exhaust.
  • the engine body 1 includes a combustion chamber 2 as each cylinder, an electronically controlled fuel injection valve 3 for injecting fuel into each combustion chamber 2, an intake manifold 4, and an exhaust manifold 5.
  • the intake manifold 4 is connected to the outlet of the compressor 7 a of the exhaust turbocharger 7 through the intake duct 6.
  • An inlet of the compressor 7 a is connected to an air cleaner 9 via an intake air amount detector 8.
  • a throttle valve 10 driven by a step motor is disposed in the intake duct 6.
  • a cooling device 11 for cooling the intake air flowing through the intake duct 6 is disposed in the middle of the intake duct 6.
  • engine cooling water is guided to the cooling device 11.
  • the intake air is cooled by the engine cooling water.
  • the exhaust manifold 5 is connected to the inlet of the exhaust turbine 7b of the exhaust turbocharger 7.
  • the outlet of the exhaust turbine 7 b is connected to the inlet of the exhaust purification catalyst 13 through the exhaust pipe 12.
  • the outlet of the exhaust purification catalyst 13 is connected to a particulate filter 14 that collects particulates contained in the exhaust through an exhaust pipe 12a.
  • a hydrocarbon supply valve 15 is provided upstream of the exhaust purification catalyst 13 for supplying hydrocarbons made of light oil or other fuel used as fuel for the compression ignition internal combustion engine.
  • light oil is used as the hydrocarbon supplied from the hydrocarbon supply valve 15.
  • the present invention can also be applied to a spark ignition type internal combustion engine in which the air-fuel ratio at the time of combustion is controlled to be lean.
  • the hydrocarbon supply valve supplies gasoline used as fuel for the spark ignition type internal combustion engine or hydrocarbons made of other fuels.
  • An EGR passage 16 is disposed between the exhaust manifold 5 and the intake manifold 4 for exhaust gas recirculation (EGR).
  • An electronically controlled EGR control valve 17 is disposed in the EGR passage 16.
  • a cooling device 18 for cooling the EGR gas flowing in the EGR passage 16 is disposed in the middle of the EGR passage 16. In the embodiment shown in FIG. 1, engine cooling water is introduced into the cooling device 18. The EGR gas is cooled by the engine cooling water.
  • Each fuel injection valve 3 is connected to a common rail 20 via a fuel supply pipe 19.
  • the common rail 20 is connected to a fuel tank 22 via an electronically controlled variable discharge amount fuel pump 21.
  • the fuel stored in the fuel tank 22 is supplied into the common rail 20 by the fuel pump 21.
  • the fuel supplied into the common rail 20 is supplied to the fuel injection valve 3 through each fuel supply pipe 19.
  • the electronic control unit 30 is composed of a digital computer.
  • the electronic control unit 30 in the present embodiment functions as a control device for the exhaust purification device.
  • the electronic control unit 30 includes a ROM (Read Only Memory) 32, a RAM (Random Access Memory) 33, a CPU (Microprocessor) 34, an input port 35 and an output port 36 that are connected to each other by a bidirectional bus 31.
  • the ROM 32 stores in advance information such as a map necessary for control.
  • the CPU 34 can perform arbitrary calculations and determinations.
  • the RAM 33 can store information such as an operation history and can store calculation results.
  • a temperature sensor 23 for detecting the temperature of the exhaust purification catalyst 13 is attached downstream of the exhaust purification catalyst 13. Further, a temperature sensor 25 for detecting the temperature of the particulate filter 14 is attached downstream of the particulate filter 14.
  • a differential pressure sensor 24 for detecting the differential pressure before and after the particulate filter 14 is attached to the particulate filter 14.
  • the output signals of the temperature sensors 23 and 25, the differential pressure sensor 24, and the intake air amount detector 8 are input to the input port 35 via corresponding AD converters 37, respectively.
  • a load sensor 41 that generates an output voltage proportional to the amount of depression of the accelerator pedal 40 is connected to the accelerator pedal 40. The output voltage of the load sensor 41 is input to the input port 35 via the corresponding AD converter 37.
  • the input port 35 is connected to a crank angle sensor 42 that generates an output pulse every time the crankshaft rotates, for example, 15 °. From the output of the crank angle sensor 42, the crank angle and the engine speed can be detected.
  • the output port 36 is connected to the fuel injection valve 3, the step motor for driving the throttle valve 10, the hydrocarbon supply valve 15, the EGR control valve 17, and the fuel pump 21 through corresponding drive circuits 38.
  • the fuel injection valve 3, the throttle valve 10, the hydrocarbon supply valve 15, the EGR control valve 17, and the like are controlled by the electronic control unit 30.
  • the particulate filter 14 is a filter that removes particulate matter (particulates) such as carbon fine particles and sulfate contained in the exhaust gas.
  • the particulate filter 14 has, for example, a honeycomb structure and a plurality of flow paths extending in the gas flow direction. In the plurality of channels, the channels whose downstream ends are sealed and the channels whose upstream ends are sealed are alternately formed.
  • the partition walls of the flow path are formed of a porous material such as cordierite. Particulates are captured when the exhaust passes through the partition wall. Particulate matter is collected by the particulate filter 14.
  • the particulate matter that gradually accumulates on the particulate filter 14 is oxidized and removed by raising the temperature to, for example, about 650 ° C. in an atmosphere with excess air.
  • FIG. 2 is an enlarged view of the surface portion of the catalyst carrier carried on the substrate of the exhaust purification catalyst in the present embodiment.
  • the exhaust purification catalyst 13 includes a base including a passage through which exhaust flows.
  • a catalyst carrier 50 for supporting catalyst particles 51 and 52 as noble metal catalysts is disposed on the surface of the passage of the substrate.
  • noble metal catalyst particles 51 and 52 are supported on a catalyst carrier 50 made of alumina, for example.
  • an alkali metal such as potassium K, sodium Na, cesium Cs, an alkaline earth metal such as barium Ba or calcium Ca, a rare earth such as a lanthanoid and silver Ag, copper Cu, iron Fe, NO like iridium Ir X
  • a basic layer 53 containing at least one selected from metals capable of donating electrons is formed.
  • the noble metal catalyst particles 51 and 52 are supported on the exhaust gas flow surface of the exhaust gas purification catalyst 13. Further, since the surface of the basic layer 53 exhibits basicity, the surface of the basic layer 53 is referred to as a basic exhaust circulation surface portion 54.
  • the noble metal catalyst particles 51 are made of platinum Pt
  • the noble metal catalyst particles 52 are made of rhodium Rh. That is, the noble metal catalyst particles 51 and 52 carried on the catalyst carrier 50 are composed of platinum Pt and rhodium Rh.
  • FIG. 3 schematically shows the hydrocarbon reforming action performed in the exhaust purification catalyst of the present embodiment. As shown in FIG. 3, the hydrocarbon HC injected from the hydrocarbon feed valve 15 becomes a radical hydrocarbon HC having a small number of carbons due to the catalytic action of the catalyst particles 51.
  • FIG. 3 schematically shows the hydrocarbon reforming action performed in the exhaust purification catalyst of the present embodiment. As shown in FIG. 3, the hydrocarbon HC injected from the hydrocarbon feed valve 15 becomes a radical hydrocarbon HC having a small number of carbons due to the catalytic action of the catalyst particles 51.
  • the exhaust air-fuel ratio (A / F) of exhaust gas flowing into the exhaust purification catalyst is referred to as the exhaust air-fuel ratio (A / F).
  • Air-fuel ratio (A / F) of exhaust gas flowing into the exhaust purification catalyst in Since this change depends on the change in the concentration of hydrocarbons in the exhaust gas flowing into the exhaust purification catalyst 13, the air-fuel ratio (A / F) shown in FIG. in It can be said that the change in represents the change in hydrocarbon concentration.
  • FIG. 5 shows the catalyst temperature and NO of the exhaust purification catalyst in this embodiment.
  • X It is a graph which shows the relationship with a purification rate.
  • FIG. 5 shows the air-fuel ratio (A / F) of the exhaust gas flowing into the exhaust purification catalyst 13 as shown in FIG. in NO when cyclically changing X
  • the purification rate is shown with respect to the catalyst temperature TC of the exhaust purification catalyst 13.
  • the inventor has NO over a long period of time.
  • FIG. 6A and 6B schematically show the surface portion of the catalyst carrier of the exhaust purification catalyst.
  • FIG. 6A and FIG. 6B show a reaction that is assumed to occur when the concentration of hydrocarbons flowing into the exhaust purification catalyst is vibrated with an amplitude within a predetermined range and a period within a predetermined range.
  • Has been. 6A shows a case where the concentration of hydrocarbons flowing into the exhaust purification catalyst 13 is low.
  • FIG. 6B shows the concentration of hydrocarbons supplied from the hydrocarbon supply valve 15 and flowing into the exhaust purification catalyst 13. Shows when is high.
  • the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst 13 is maintained lean except for a moment.
  • the exhaust flowing into the exhaust purification catalyst 13 is normally in an oxygen-excess state. Therefore, the NO contained in the exhaust is oxidized on the platinum catalyst particles 51 as shown in FIG. 2 And then this NO 2 Is further oxidized to NO 3 It becomes. NO 2 Part of is NO 2 ⁇ It becomes. In this case, NO 3 The amount of production is NO 2 ⁇ Much more than the amount of product. Therefore, a large amount of NO is present on the platinum catalyst particles 51. 3 And a small amount of NO 2 ⁇ Will be generated. These NO 3 And NO 2 ⁇ Is highly active. In the present invention, these NOs 3 And NO 2 ⁇ Active NO X The symbol NO X * Is shown.
  • active NO X NO in the form of X Is retained. That is, on the basic exhaust flow surface portion 54, NO contained in the exhaust gas is present. X Is retained.
  • hydrocarbons are supplied from the hydrocarbon supply valve 15, the hydrocarbons are reformed in the exhaust purification catalyst 13 as shown in FIG. 3, and become radicals. As a result, as shown in FIG. X The surrounding hydrocarbon concentration increases.
  • active NO X After NO is generated, active NO X If the surrounding oxygen concentration is high for more than a certain period of time, active NO X Is oxidized and nitrate ion NO 3 ⁇ In the basic layer 53.
  • the active NO X When the surrounding hydrocarbon concentration is increased, as shown in FIG. X Reacts with the radical hydrocarbon HC on the catalyst particles 51, thereby producing a reducing intermediate.
  • This reducing intermediate is held on the surface of the basic layer 53.
  • the first reducing intermediate produced at this time is the nitro compound R-NO. 2 It is thought that.
  • This nitro compound R-NO 2 When produced, it becomes the nitrile compound R-CN. Since this nitrile compound R-CN can only survive for a moment in that state, it immediately becomes an isocyanate compound R-NCO. When this isocyanate compound R-NCO is hydrolyzed, the amine compound R-NH 2 It becomes.
  • the reducing intermediate and the active NO X Will react.
  • NO X Will be purified.
  • a reducing intermediate is generated by increasing the concentration of hydrocarbons flowing into the exhaust purification catalyst 13, and the concentration of hydrocarbons flowing into the exhaust purification catalyst 13 is decreased to reduce the oxygen concentration.
  • the exhaust purification catalyst 13 makes NO. X In order to purify, it is necessary to periodically change the concentration of hydrocarbons flowing into the exhaust purification catalyst 13.
  • the produced reducing intermediate is activated NO. X It is necessary to reduce the hydrocarbon concentration to a concentration low enough to react with. That is, it is necessary to vibrate the concentration of hydrocarbons flowing into the exhaust purification catalyst 13 with an amplitude within a predetermined range. In this case, the generated reducing intermediate is active NO. X Sufficient amounts of reducing intermediates R-NCO and R-NH until 2 Must be retained on the basic layer 53, that is, on the basic exhaust flow surface portion 54, for which a basic exhaust flow surface portion 54 is provided.
  • reducing intermediates R-NCO and R-NH 2 In order to keep the inside of the exhaust purification catalyst 13, a basic exhaust flow surface portion 54 is formed around the noble metal catalyst particles 51 and 52. Reducing intermediates R-NCO and R-NH retained on the basic exhaust flow surface portion 54 2 NO X Is reduced, and the vibration period of the hydrocarbon concentration is reduced by reducing intermediates R-NCO and R-NH. 2 Is the oscillation period necessary to continue to generate Incidentally, in the example shown in FIG. 4, the injection interval is 3 seconds.
  • the basic layer 53 at this time X NO for temporary storage X It plays the role of a storage agent.
  • the exhaust purification catalyst 13 is NO when the air-fuel ratio of the exhaust is lean.
  • X NO is occluded when the oxygen concentration in the exhaust gas decreases.
  • X NO release X It functions as a storage catalyst.
  • Fig. 9 shows NO exhaust purification catalyst X NO when functioning as a storage catalyst X The purification rate is shown.
  • the horizontal axis in FIG. 9 indicates the catalyst temperature TC of the exhaust purification catalyst 13.
  • the new NO shown in FIGS. 4 to 6A and 6B X In the purification method, as can be seen from FIGS. 6A and 6B, nitrate is not produced or is produced in a very small amount, and as a result, as shown in FIG. 5, even when the catalyst temperature TC is high, the NO is high. X A purification rate will be obtained. Therefore, in the present invention, the hydrocarbon supply valve 15 for supplying hydrocarbons is arranged in the engine exhaust passage, and NO contained in the exhaust in the engine exhaust passage downstream of the hydrocarbon supply valve 15.
  • An exhaust purification catalyst 13 for reacting the catalyst with the reformed hydrocarbon is disposed, and noble metal catalyst particles 51, 52 are supported on the exhaust flow surface of the exhaust purification catalyst 13, and noble metal catalyst particles 51 are supported.
  • , 52 is formed with a basic exhaust flow surface portion 54, and the exhaust purification catalyst 13 determines the concentration of hydrocarbons flowing into the exhaust purification catalyst 13 within a predetermined range and a predetermined range. NO contained in exhaust when oscillated with a period within the range X NO is contained in the exhaust gas when the vibration period of the hydrocarbon concentration is longer than this predetermined range.
  • the hydrocarbon concentration flowing into the exhaust purification catalyst 13 during engine operation is vibrated with an amplitude within a predetermined range and a period within a predetermined range, As a result, NO contained in the exhaust X Is reduced in the exhaust purification catalyst 13. That is, the NO shown in FIGS. 4 to 6A and 6B X
  • the purification method carries noble metal catalyst particles, and NO. X In the case of using an exhaust purification catalyst having a basic layer capable of absorbing NO, NO hardly forms nitrates.
  • X New NO to purify X It can be said that it is a purification method. In fact, this new NO X When the purification method is used, the exhaust purification catalyst 13 is set to NO.
  • the purification method is the first NO X This is called a purification method.
  • the purification method will be described in a little more detail. 10 is the air-fuel ratio (A / F) shown in FIG. in The change is shown enlarged. As described above, the air-fuel ratio (A / F) of the exhaust gas flowing into the exhaust purification catalyst 13 in This change simultaneously indicates a change in the concentration of hydrocarbons flowing into the exhaust purification catalyst 13. In FIG.
  • ⁇ H indicates the amplitude of the change in the concentration of hydrocarbon HC flowing into the exhaust purification catalyst 13, and ⁇ T indicates the oscillation period of the concentration of hydrocarbon flowing into the exhaust purification catalyst 13.
  • (A / F) b Represents a base air-fuel ratio indicating an air-fuel ratio of combustion gas for generating engine output.
  • this base air-fuel ratio (A / F) b Represents the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst 13 when the supply of hydrocarbons is stopped.
  • X represents the generated active NO. X Is used for the production of the reducing intermediate without being occluded in the basic layer 53 in the form of nitrate.
  • X in Fig. 10 is active NO X Represents the lower limit of the hydrocarbon concentration required to produce a reducing intermediate by reacting the modified hydrocarbon with the modified hydrocarbon. It is necessary to make it higher than the lower limit X. In this case, whether or not a reducing intermediate is generated depends on the active NO.
  • the above-mentioned upper limit X of the air-fuel ratio necessary for generating the reducing intermediate is hereinafter referred to as a required minimum air-fuel ratio.
  • the required minimum air-fuel ratio X is rich. Therefore, in this case, the air-fuel ratio (A / F) is used to generate a reducing intermediate. in Is instantaneously made below the required minimum air-fuel ratio X, that is, made rich. On the other hand, in the example shown in FIG. 11, the required minimum air-fuel ratio X is lean.
  • air-fuel ratio (A / F) in Air-fuel ratio (A / F) while maintaining lean in Reducing intermediates are produced by periodically reducing.
  • whether the required minimum air-fuel ratio X becomes rich or lean depends on the oxidizing power of the exhaust purification catalyst 13.
  • the exhaust purification catalyst 13 increases its oxidizing power if, for example, the amount of precious metal catalyst particles 51 is increased, and its oxidizing power increases if its acidity is increased. Therefore, the oxidizing power of the exhaust purification catalyst 13 varies depending on the amount of the precious metal catalyst particles 51 supported and the acidity. Now, when the exhaust purification catalyst 13 having a strong oxidizing power is used, as shown in FIG.
  • the air-fuel ratio (A / F) in Air-fuel ratio (A / F) while maintaining lean in Is periodically reduced the air-fuel ratio (A / F) in When the amount is lowered, the hydrocarbon is completely oxidized, and as a result, a reducing intermediate cannot be produced.
  • the exhaust purification catalyst 13 having a strong oxidizing power is used, as shown in FIG. 10, the air-fuel ratio (A / F) in The air-fuel ratio (A / F) is made rich periodically in When is enriched, hydrocarbons are partially oxidized without being completely oxidized. That is, the hydrocarbon is reformed to produce a reducing intermediate.
  • the exhaust purification catalyst 13 having a strong oxidizing power when used, the required minimum air-fuel ratio X needs to be made rich.
  • the exhaust purification catalyst 13 with weak oxidizing power when used, as shown in FIG. 11, the air-fuel ratio (A / F) in Air-fuel ratio (A / F) while maintaining lean in
  • the hydrocarbons are not completely oxidized but partially oxidized. That is, the hydrocarbon is reformed to produce a reducing intermediate.
  • the exhaust purification catalyst 13 having a weak oxidizing power when the exhaust purification catalyst 13 having a weak oxidizing power is used, as shown in FIG.
  • NO X In order to purify the water well, it is necessary to oxidize excess hydrocarbons as described above. Therefore NO X In order to purify the water well, a larger amount of excess hydrocarbon requires more oxygen. In this case, the amount of oxygen can be increased by increasing the oxygen concentration in the exhaust. Therefore NO X In order to purify the gas well, it is necessary to increase the oxygen concentration in the exhaust after the hydrocarbon is supplied when the oxygen concentration in the exhaust before the hydrocarbon is supplied is high. That is, it is necessary to increase the amplitude of the hydrocarbon concentration as the oxygen concentration in the exhaust before the hydrocarbon is supplied is higher.
  • Figure 13 shows the same NO X
  • the relationship between the oxygen concentration in the exhaust gas before the hydrocarbons are supplied and the amplitude ⁇ H of the hydrocarbon concentration when the purification rate is obtained is shown.
  • the same NO from FIG. X It can be seen that in order to obtain a purification rate, it is necessary to increase the amplitude ⁇ H of the hydrocarbon concentration as the oxygen concentration in the exhaust before the hydrocarbon is supplied is higher. That is, the same NO X Base air / fuel ratio (A / F) to obtain purification rate b It becomes necessary to increase the amplitude ⁇ H of the hydrocarbon concentration as the value becomes higher.
  • NO X Air / fuel ratio (A / F) b As the value becomes lower, the amplitude ⁇ H of the hydrocarbon concentration can be reduced.
  • base air-fuel ratio (A / F) b Is the lowest during acceleration operation. At this time, if the amplitude ⁇ H of the hydrocarbon concentration is about 200 ppm, NO X Can be purified well.
  • Base air-fuel ratio (A / F) b Is usually larger than that during acceleration operation. Therefore, as shown in FIG. 14, when the amplitude ⁇ H of the hydrocarbon concentration is 200 ppm or more, good NO is obtained. X A purification rate can be obtained.
  • base air-fuel ratio (A / F) b NO is good when the amplitude ⁇ H of the hydrocarbon concentration is about 10000 ppm.
  • the predetermined range of the amplitude of the hydrocarbon concentration is set to 200 ppm to 10,000 ppm.
  • the active NO is X The surrounding oxygen concentration becomes high. In this case, when the vibration period ⁇ T of the hydrocarbon concentration is longer than about 5 seconds, the active NO X Begins to be absorbed into the basic layer 53 in the form of nitrate. Therefore, as shown in FIG.
  • the vibration period ⁇ T of the hydrocarbon concentration needs to be 5 seconds or less.
  • the vibration period ⁇ T of the hydrocarbon concentration becomes approximately 0.3 seconds or less, the supplied hydrocarbon starts to accumulate on the exhaust gas distribution surface of the exhaust purification catalyst 13. Therefore, as shown in FIG. 15, when the vibration period ⁇ T of the hydrocarbon concentration becomes approximately 0.3 seconds or less, NO X The purification rate decreases. Therefore, in the present invention, the vibration period of the hydrocarbon concentration is set to be between 0.3 seconds and 5 seconds. Next, turn the exhaust purification catalyst to NO while referring to FIGS.
  • the exhaust purification catalyst 13 is set to NO. X NO when functioning as a storage catalyst X
  • the purification method is the second NO X This is called a purification method.
  • Fig. 16 shows NO in the second purification method.
  • X Shows a time chart when purifying. 2nd NO X
  • the storage NO stored in the basic layer 53 is stored.
  • X The air-fuel ratio (A / F) of the exhaust flowing into the exhaust purification catalyst 13 when the amount ⁇ NOX exceeds a predetermined allowable amount MAX in Is temporarily rich.
  • Exhaust air-fuel ratio (A / F) in Is made rich, the air-fuel ratio (A / F) of the exhaust in NO stored in the basic layer 53 when is lean X Are released from the basic layer 53 at once and reduced.
  • Occlusion NO X The amount ⁇ NOX is, for example, NO discharged from the engine X Calculated from the quantity. In an embodiment according to the present invention, NO discharged from the engine per unit time X
  • the emission amount NOXA is stored in advance in the ROM 32 as a function of the injection amount Q and the engine speed N in the form of a map as shown in FIG. This NO X NOxA from storage NOXA X An amount ⁇ NOX is calculated.
  • the air-fuel ratio (A / F) of the exhaust gas in The period during which is made rich is usually 1 minute or more.
  • Second NO in this embodiment X In the purification method, as shown in FIG. 18, the air-fuel ratio (A) of the exhaust gas flowing into the exhaust purification catalyst 13 by injecting additional fuel WR in addition to the combustion fuel Q from the fuel injection valve 3 into the combustion chamber 2. / F) in Is made rich.
  • the horizontal axis in FIG. 18 indicates the crank angle.
  • the additional fuel WR in the present embodiment is injected at a time when it burns but does not appear as engine output, that is, slightly before ATDC 90 ° after compression top dead center.
  • This fuel amount WR is stored in advance in the ROM 32 as a function of the injection amount Q and the engine speed N in the form of a map as shown in FIG.
  • the air / fuel ratio (A / F) of the exhaust gas is increased by increasing the amount of hydrocarbons supplied from the hydrocarbon supply valve 15. in Can also be made richer.
  • the first NO again X Returning to the explanation of the purification method, the first NO X NO using the purification method X As described above, it is necessary to appropriately control the amplitude ⁇ H and the vibration period ⁇ T of the hydrocarbon concentration.
  • the first NO X NO using the purification method X In order to purify the exhaust gas well, the air-fuel ratio (A / F) of the exhaust gas flowing into the exhaust gas purification catalyst 13 in Therefore, it is necessary to control the amplitude ⁇ H of the hydrocarbon concentration so as to be less than the required minimum air-fuel ratio X and to control the oscillation period ⁇ T of the hydrocarbon concentration between 0.3 seconds and 5 seconds.
  • the amplitude ⁇ H of the hydrocarbon concentration is controlled by controlling the injection amount of hydrocarbons from the hydrocarbon feed valve 15, and the vibration period ⁇ T of the hydrocarbon concentration is controlled by the hydrocarbon feed valve 15. It is controlled by controlling the hydrogen injection period.
  • the injection amount of hydrocarbons from the hydrocarbon supply valve 15 can be controlled by changing at least one of the injection time or injection pressure of hydrocarbons from the hydrocarbon supply valve 15.
  • the first NO X NO by purification method X When the purification action is being performed, what is most required is high NO in any operating condition X A purification rate can be obtained, and the supplied hydrocarbon is prevented from passing through the exhaust purification catalyst 13.
  • the amount of hydrocarbons that are completely oxidized and the amount of partially oxidized hydrocarbons in the exhaust purification catalyst 13 are NO X It has been found that it controls the purification rate and the amount of hydrocarbon slip-through. Next, this will be described with reference to FIG. FIG.
  • FIG. 20 shows three injection patterns A, B, and C of hydrocarbons injected from the hydrocarbon supply valve at different injection times under the same injection pressure.
  • the injection pattern A has the shortest injection pattern A and the injection pattern C has the longest injection time.
  • FIG. 20 shows temporal changes in the hydrocarbon concentration in the exhaust gas flowing into the exhaust purification catalyst 13 after the injection is performed by the respective injection patterns A, B, and C. Further, FIG. 20 shows NO when the injection patterns A, B, and C are performed.
  • X The purification rate and the amount of hydrocarbons that pass through the exhaust purification catalyst 13 are shown.
  • the hydrocarbon concentration in the exhaust has a limit at which all hydrocarbons are completely oxidized in the exhaust purification catalyst 13, and this limit is indicated by XA in FIG. That is, in FIG.
  • the hatched region RB represents the amount of hydrocarbons that are partially oxidized. Since the reducing intermediate is generated from the partially oxidized hydrocarbon, the first NO is generated by the partially oxidized hydrocarbon. X NO by purification method X The purifying action is performed. Actually, a part of the partially oxidized hydrocarbon is oxidized without being used for the production of the reducing intermediate, and the reducing intermediate is produced by the remaining partially oxidized hydrocarbon. On the other hand, when the concentration of hydrocarbons in the exhaust gas flowing into the exhaust purification catalyst 13, that is, the amount of hydrocarbons per unit exhaust amount further increases, some of the hydrocarbons are not completely oxidized in the exhaust purification catalyst 13, but are also partially oxidized.
  • FIG. 20 shows a case where the amount of hydrocarbon RB to be partially oxidized is insufficient as described above. In this case, as shown in FIG. X The purification rate will decrease.
  • the injection pattern B shows a case where the injection time is made longer than that of the injection pattern A in order to increase the amount of partially oxidized hydrocarbon RB. As the injection time is increased, the amount of hydrocarbons shown in the region RB that is partially oxidized increases. X The purification rate increases. Note that FIG. 20 shows a case where the hydrocarbon amount RB partially oxidized is slightly insufficient even in the injection pattern B.
  • the injection pattern C shows a case where the injection time is further increased compared to the injection pattern B in order to further increase the amount of partially oxidized hydrocarbon RB.
  • the purification rate is improved.
  • the hydrocarbon concentration exceeds the slip-through limit XB, so that hydrocarbon slip-through occurs.
  • FIG. 21 shows an example when hydrocarbon injection control is performed in consideration of this. Note that the example shown in FIG. 21 shows a case in which the injection amount of hydrocarbons is controlled by controlling the injection time while maintaining the injection pressure constant.
  • the hydrocarbon injection amount can be adjusted by controlling the injection pressure.
  • an injection pattern A1 shows when the engine speed and load are relatively low
  • an injection pattern A3 shows when the engine speed and load are relatively high
  • an injection pattern A2 shows the engine speed and load.
  • the case where the load is intermediate between the case indicated by the injection pattern A1 and the case indicated by the injection pattern A3 is shown. That is, the injection pattern is changed from A1 to A3 as the engine speed and load increase.
  • the higher the engine speed and load the higher the temperature of the exhaust purification catalyst 13, and the higher the engine speed and load, the higher the complete oxidation limit XA and the slip-through limit XB.
  • the amount of hydrocarbon RB that is partially oxidized needs to be increased as the amount increases, and as the engine speed and load increase.
  • NO X in order to increase the amount RB of partially oxidized hydrocarbons, it is necessary to increase the injection amount of hydrocarbons. Therefore NO X
  • the injection amount is increased by increasing the injection time as the engine speed and load increase so that the amount of partially oxidized hydrocarbons necessary for the purification of can be generated.
  • an operation state in which the particulate filter described later is regenerated is excluded from the normal operation.
  • NO held by the exhaust gas purification catalyst X Quantity and NO X The holding speed of the X Quantity and NO X Based on the holding speed, the timing for supplying hydrocarbons from the hydrocarbon supply valve and the amount of hydrocarbon supply are set. Referring to FIG. 6A and FIG. 6B, as described above, the first NO X In the purification method, the exhaust gas flowing into the exhaust purification catalyst 13 is activated NOx while the oxygen is excessive. X Is formed. Active NO X Is retained on the surface of the basic layer 53, so that NO contained in the exhaust gas X Can be removed.
  • NO in exhaust X Of the exhaust purification catalyst 13 that holds the catalyst on the surface of the basic layer is finite, and NO is reduced when the holding capacity is reduced.
  • X Cannot be sufficiently removed from the exhaust.
  • the active NO of the exhaust purification catalyst 13 X Has a finite amount of active NO X The greater the amount of carbon retained, the more NO contained in the exhaust X NO is the speed to hold X The holding speed of is reduced.
  • NO X When the holding speed of the exhaust gas decreases, the NO that can not be held by the exhaust purification catalyst and passes through the exhaust purification catalyst X The amount increases. Like this, NO X When the holding speed of X The purification rate is reduced.
  • the exhaust purification catalyst 13 in this embodiment is NO per unit time.
  • the holdable speed which is the maximum amount that can be held.
  • the holdable speed depends on the operating state of the internal combustion engine, such as the state of the exhaust purification catalyst and the operating state of the engine body.
  • the first NO X The holdable speed is estimated during the period when the purification method is performed.
  • the NO of the exhaust purification catalyst 13 X Estimate the holding capacity of The timing for supplying hydrocarbons from the hydrocarbon supply valve 15 is set based on the estimated holding capacity.
  • the NO of the exhaust purification catalyst 13 X As the retention capacity of the exhaust purification catalyst 13 X The purification rate is adopted.
  • FIG. 22 shows a flowchart of operation control during normal operation of the internal combustion engine in the present embodiment.
  • the control shown in FIG. 22 can be repeatedly performed at predetermined time intervals, for example.
  • X The amount NOXA is estimated.
  • X The amount is NO per unit time discharged from the engine body. X It is equal to the quantity NOXA.
  • the amount NOXA can be estimated by, for example, a map that is a function of the engine speed N and the fuel injection amount Q in the combustion chamber shown in FIG.
  • the required holding speed VHR is NO that flows into the exhaust purification catalyst per unit time.
  • X It can be set by multiplying the amount NOXA by a predetermined purification rate.
  • step 103 the NO of the exhaust purification catalyst X
  • the holdable speed VH is estimated. That is, from the exhaust gas per unit time by the exhaust purification catalyst 13, NO is emitted.
  • FIG. 23 shows the active NO of the exhaust purification catalyst in the present embodiment.
  • X The graph explaining the relationship between holding
  • the speed at which the exhaust purification catalyst 13 can be held is the NO held by the exhaust purification catalyst 13.
  • X Amount of active NO X Depends on the amount retained. Active NO X The higher the holding amount, the lower the holding speed. For this purpose, active NO X
  • the holdable speed VH can be estimated based on the hold amount. In this embodiment, the active NO estimated for each predetermined time interval X
  • the holding amount ACNOXW is read. Active NO X Control for estimating the holding amount at predetermined time intervals will be described later.
  • the holdable speed VH of the exhaust purification catalyst 13 can be estimated based on the hold amount.
  • NO of exhaust purification catalyst X Is the active NO.
  • the holding amount depends on other operating states of the internal combustion engine.
  • the holdable speed of the exhaust purification catalyst depends on the space velocity in the exhaust purification catalyst, the temperature of the exhaust purification catalyst, and the like.
  • the operating state of the internal combustion engine may be detected, and the holdable speed may be corrected based on the detected operating state of the internal combustion engine.
  • the first NO X NO in exhaust purification catalyst in purification method X An example of the control for estimating the amount of retention will be described.
  • FIG. 24 shows the active NO retained in the exhaust purification catalyst.
  • X It is a flowchart of control which estimates holding
  • the control for estimating the holding amount can be performed independently of the control for supplying hydrocarbons shown in FIG.
  • the NO of the exhaust purification catalyst X Active NO using the holdable speed of X Estimate the amount retained.
  • NOXA is estimated.
  • the holdable speed VH is estimated.
  • NO X As the holdable speed VH of, for example, NO estimated most recently X A holdable speed VH can be used.
  • step 113 the NO of the exhaust purification catalyst X NOH flowing into the exhaust purification catalyst per unit time X It is determined whether or not the amount is NOXA or more.
  • step 113 the holdable speed VH flows in per unit time.
  • the routine proceeds to step 114.
  • NO of the exhaust purification catalyst X NO2 flowing into the exhaust purification catalyst X It can be determined that almost all of the amount is retained by the exhaust purification catalyst.
  • step 114 NO per unit time flowing into the exhaust purification catalyst X
  • the amount of NOXA is the previous active NO X By multiplying the elapsed time ⁇ t from the calculation of the retained amount, the active NO X The amount of increase is calculated.
  • Active NO X Increase amount (NOXA ⁇ ⁇ t) is the previously calculated activity NO X By adding to the holding amount ACNOXW, the current activation NO X The holding amount can be calculated.
  • NO X NOH per unit time of flowing into the exhaust purification catalyst X If it is less than the amount NOXA, the routine proceeds to step 115. In this case, the NO flowing into the exhaust purification catalyst X Exhaust purification catalyst NO X It is possible to determine that the holding capacity of is small.
  • NO X The previous active NO at the holdable speed VH of X By multiplying the elapsed time ⁇ t from the calculation of the retained amount, the active NO X Can be calculated (VH ⁇ ⁇ t).
  • step 104 the NO of the exhaust purification catalyst is determined. X It is determined whether the holdable speed VH is equal to or higher than the required hold speed VHR. NO X If the holdable speed VH is equal to or higher than the required hold speed VHR, the NO X Therefore, it can be determined that hydrocarbons are not supplied from the hydrocarbon supply valve in this control. In this case, the current operation control is terminated. In step 104, NO of the exhaust purification catalyst X When the holdable speed VH is less than the required hold speed VHR, the routine proceeds to step 105.
  • the hydrocarbons are supplied from the hydrocarbon supply valve, and the active NO held on the exhaust purification catalyst X Control to reduce and remove
  • a supply amount WM of hydrocarbon supplied from the hydrocarbon supply valve is set.
  • the active NO of the exhaust purification catalyst X Based on the holding amount, the current hydrocarbon supply amount WM is set.
  • Fig. 25 shows the active NO retained in the exhaust purification catalyst.
  • Active NO X It can be set so that the supply amount WM of hydrocarbons supplied to the exhaust purification catalyst increases as the holding amount ACNOXW increases. Active NO X Based on the holding amount, the hydrocarbon supply amount WM can be set. In the present embodiment, almost all active NO retained in the exhaust purification catalyst. X The amount of hydrocarbons to be supplied is set so that it can be removed. By the way, the generation efficiency of the reducing intermediate varies depending on the operating state of the internal combustion engine. Therefore, in setting the hydrocarbon supply amount, the hydrocarbon supply amount may be corrected based on the operating state of the internal combustion engine.
  • the oxygen concentration of the exhaust gas flowing into the exhaust purification catalyst, the space velocity in the exhaust purification catalyst, or the like may be estimated, and the hydrocarbon supply amount may be corrected based on the estimated oxygen concentration or the like. Absent.
  • step 106 hydrocarbon is supplied from the hydrocarbon supply valve at the set hydrocarbon supply amount.
  • NO from the exhaust purification catalyst X Can be removed.
  • step 107 the exhaust purification catalyst active NO X The holding amount ACNOXW is reset.
  • the supply amount of hydrocarbons supplied from the hydrocarbon supply valve is the active NO held in the exhaust purification catalyst.
  • X It is set to an amount that can remove almost all of. Therefore, in the present embodiment, the active NO of the exhaust purification catalyst X Controls the holding amount to zero.
  • active NO X Retention amount and NO X The supply timing of hydrocarbons and the supply amount of hydrocarbons are set based on the holdable speed. By performing this control, the amount of hydrocarbons supplied is too small and the active NO retained in the exhaust purification catalyst. X Can not be reduced sufficiently, or it is possible to suppress the wasteful consumption of hydrocarbons due to excessive supply of hydrocarbons.
  • the supply cycle when supplying hydrocarbons to the engine exhaust passage is shortened, and The amount of one-time supply of hydrocarbons increases.
  • the supply cycle for supplying hydrocarbons becomes longer, and the amount of hydrocarbons supplied at one time decreases.
  • the exhaust gas purification apparatus for an internal combustion engine in the present embodiment includes a particulate filter 14 as an aftertreatment device.
  • the particulate filter 14 is disposed downstream of the exhaust purification catalyst 13. When the operation of the internal combustion engine is continued, particulate matter accumulates on the particulate filter 14.
  • the amount of particulate matter deposited can be estimated, for example, from the differential pressure before and after the particulate filter 14 detected by the differential pressure sensor 24.
  • regeneration is performed by oxidizing and removing the particulate matter by increasing the temperature of the particulate filter 14.
  • temperature rise control is performed to raise the temperature of the particulate filter 14 to a target temperature.
  • the exhaust purification catalyst of the present embodiment has a function of oxidizing hydrocarbons. Hydrocarbon can be supplied to the exhaust purification catalyst 13 to cause an oxidation reaction. In the exhaust purification catalyst 13, the temperature of the exhaust gas rises due to the occurrence of a hydrocarbon oxidation reaction.
  • the temperature of the particulate filter 14 can be raised to the target temperature.
  • control is performed to maintain the particulate filter 14 at the target temperature.
  • hydrocarbons are supplied from the hydrocarbon supply valve in consideration of the temperature rise of the exhaust with respect to the temperature of the exhaust discharged from the engine body.
  • heat generated in the exhaust purification catalyst heat generated by direct oxidation of hydrocarbons, reducing intermediates are generated from the hydrocarbons, and the reducing intermediates are active NO. X And heat generated when reacting with.
  • the temperature of the exhaust gas flowing into the particulate filter can be raised. 650 ° C. can be exemplified as the target temperature for regenerating the particulate filter.
  • the temperature of the exhaust purification catalyst 13 becomes a temperature corresponding to the target temperature of the particulate filter 14. For this reason, the exhaust purification catalyst 13 also becomes high temperature. Even in such a high temperature state, the exhaust purification catalyst 13 in the present embodiment is NO.
  • the purification rate can be kept high (see FIG. 5). In the present embodiment, even during the regeneration period of the particulate filter 14, the first NO in the exhaust purification catalyst. X NO with high purification rate due to purification method X Purification can be continued.
  • the first NO in the normal operation in order to raise the temperature of the particulate filter 14, in order to raise the temperature of the particulate filter, the first NO in the normal operation.
  • X It is necessary to supply a larger amount of hydrocarbon than the amount of hydrocarbon supplied based on the purification method. For example, in the temperature rise control, it is necessary to set the supply amount of hydrocarbons per unit time from the hydrocarbon supply valve to be larger than that in the normal operation.
  • the first NO in normal operation X NO by purification method X
  • the hydrocarbon supply timing is set by estimating the holdable speed.
  • the hydrocarbon supply cycle is equivalent to the hydrocarbon concentration oscillation cycle.
  • the first NO X The hydrocarbon can be supplied in accordance with the supply timing of the hydrocarbon when performing the purification method. That is, the first NO X It is possible to increase the supply amount of hydrocarbons per time when performing the purification method. However, if the amount necessary for raising the temperature of the particulate filter is increased, the amount of hydrocarbon supplied per time from the hydrocarbon supply valve increases, and the hydrocarbon passes through the exhaust purification catalyst. Occurs. For example, referring to FIG. 20, when an amount of hydrocarbons exceeding the slip-through limit XB is supplied in one time of supply of hydrocarbons as in a hydrocarbon injection pattern C, exhaust gas is exhausted as shown in region RC. Hydrocarbons that pass through the purification catalyst 13 are generated.
  • the hydrocarbons that have passed through the exhaust purification catalyst 13 also pass through the particulate filter 14 and are released into the atmosphere. . Even when catalyst particles having an oxidation function such as platinum are supported on the particulate filter 14, if a large amount of hydrocarbons flows into the particulate filter 14, the hydrocarbons pass through the particulate filter 14. May be released into the atmosphere. Further, when a large amount of hydrocarbons is supplied to the exhaust purification catalyst 13 at one time, the exhaust purification catalyst 13 may be overheated.
  • FIG. 26 is a graph illustrating the relationship between the hydrocarbon supply cycle and the hydrocarbon supply amount per one time supplied from the hydrocarbon supply valve in the temperature rise control of the present embodiment.
  • FIG. 26 is a graph in the operating state of one internal combustion engine.
  • the total hydrocarbons supplied to the exhaust purification catalyst based on the current temperature of the particulate filter and the target temperature for regenerating the particulate filter.
  • Supply amount is set. Further, a period (time length) during which the temperature of the particulate filter is raised is determined in advance.
  • the iso-fuel consumption line is indicated by a solid line.
  • the iso-fuel consumption line shows the amount of hydrocarbons supplied at one time when the hydrocarbon supply cycle is changed under the condition that the total supply amount of hydrocarbons and the supply period (supply time length) are constant. Yes.
  • the longer the hydrocarbon supply cycle ⁇ T the larger the hydrocarbon supply amount WM supplied from the hydrocarbon supply valve at a time. Further, the longer the hydrocarbon supply cycle ⁇ T, the smaller the number of hydrocarbons supplied.
  • FIG. 27 shows the NO when the hydrocarbon feed cycle is changed in the temperature rise control of the present embodiment.
  • X The graph explaining the purification rate of is shown.
  • FIG. 27 is a graph when operation is performed in the same operation state as that of the internal combustion engine in FIG.
  • Exhaust gas purification catalyst can be improved by changing the hydrocarbon feed cycle gradually longer.
  • X Ascending range in which the purification rate increases, and a predetermined NO X It has a high purification rate range that is greater than or equal to the purification rate EN. In the high purification rate range in the present embodiment, the high purification rate becomes substantially constant.
  • the purification rate is indicated by a broken line.
  • NO X In the temperature rise control in the present embodiment, NO X
  • the supply cycle ⁇ T and the hydrocarbon supply amount WM per time are selected.
  • the supply cycle in which the hydrocarbon supply cycle ⁇ T is the shortest in the high purification rate range is referred to as a specific supply cycle ⁇ TS.
  • the supply amount of hydrocarbons per time corresponding to the specific supply cycle ⁇ TS is referred to as a specific supply amount WMS.
  • the high purification rate range has a region WT on the end portion on the side where the hydrocarbon supply cycle is short.
  • the region WT at the end on the short supply cycle side is a region in the vicinity of the specific supply cycle ⁇ TS.
  • the region WT at the end portion on the short supply cycle side can be set to a region in which the supply cycle is increased by a predetermined time width from the specific supply cycle ⁇ TS.
  • As the region WT on the end portion on the short supply cycle side for example, a quarter region on the short supply cycle side of the high purification rate range can be exemplified.
  • control for supplying hydrocarbons is performed within the range of the region WT on the end portion on the side where the supply cycle is short.
  • the supply amount WM of hydrocarbon per time can be reduced.
  • the supply amount WM of hydrocarbons per time it is possible to suppress the passage of hydrocarbons in the exhaust purification catalyst.
  • the temperature controllability of the exhaust purification catalyst can be improved. For example, it is possible to suppress the temperature of the exhaust purification catalyst from rapidly rising and overheating.
  • FIG. 28 shows a flowchart of the temperature rise control of the exhaust purification system of the present embodiment.
  • the temperature increase control shown in FIG. 28 can be repeatedly performed at predetermined time intervals, for example, during the period of regeneration of the particulate filter.
  • step 121 the temperature of the particulate filter is detected.
  • the temperature of the particulate filter 14 can be detected by, for example, a temperature sensor 23.
  • the total supply amount of hydrocarbons for raising the temperature of the particulate filter is set.
  • the total supply amount of hydrocarbons can be set based on the current temperature of the particulate filter and the target temperature for regeneration.
  • the total supply amount HCT of hydrocarbons can be calculated by the following equation, for example.
  • HCT Ga ⁇ (TPtrg-TP) ⁇ ⁇ TP ... (1)
  • the variable Ga is the intake air flow rate and corresponds to the space velocity in the engine exhaust passage.
  • the variable TPtrg is the target temperature of the particulate filter.
  • the variable TP is the current temperature of the particulate filter.
  • Constant ⁇ TP Is a coefficient for calculating the total supply amount of hydrocarbons HCT.
  • step 123 the operating state of the internal combustion engine is detected.
  • the hydrocarbon feed cycle and NO shown in the graphs of FIGS. X The relationship with the purification rate varies depending on the operating state of the internal combustion engine. By specifying the operating state of the internal combustion engine, as shown in FIGS. X The relationship of the purification rate is determined.
  • the fuel injection amount Q and the engine speed N in the combustion chamber are detected as the operating state of the internal combustion engine.
  • step 124 a hydrocarbon supply period ⁇ T in the temperature rise control and a hydrocarbon supply amount WM per time are set. Referring to FIG.
  • FIG. 29 shows a map for setting the amount of supply of hydrocarbons per time in the temperature rise control of the present embodiment.
  • a map of the supply amount WM of hydrocarbons per time which is a function of the engine speed N and the fuel injection amount Q in the combustion chamber, is stored in advance in the electronic control unit. By detecting the engine speed N and the fuel injection amount Q, it is possible to set the hydrocarbon supply amount WM per one time.
  • the specific supply amount WMS is stored as the hydrocarbon supply amount WM. Based on the detected operating state of the internal combustion engine, it is possible to set the supply amount of hydrocarbons per one time.
  • FIG. 30 shows a map for setting the hydrocarbon supply cycle in the temperature rise control of the present embodiment.
  • a map of the hydrocarbon supply cycle ⁇ T which is a function of the engine speed N and the fuel injection amount Q in the combustion chamber, is stored in advance in the electronic control unit. By detecting the engine speed N and the fuel injection amount Q, the hydrocarbon supply period ⁇ T can be set.
  • the specific supply cycle ⁇ TS is stored as the hydrocarbon supply cycle ⁇ T.
  • the hydrocarbon supply cycle can be set.
  • the specific supply cycle and the specific supply amount are set based on the operation state of the internal combustion engine.
  • step 125 hydrocarbons are supplied from the hydrocarbon supply valve based on the set hydrocarbon supply cycle and the set hydrocarbon supply amount per time.
  • high NO X The amount of hydrocarbons supplied per time can be reduced while maintaining the purification rate.
  • the specific supply cycle ⁇ TS is selected from the values of the end region WT on the short supply cycle side has been described.
  • FIG. 31 shows a time chart of an operation example of the exhaust emission control device in the present embodiment. In the operation example shown in FIG. 31, the temperature increase control is performed during a period when the operation state of the internal combustion engine varies.
  • the temperature increase control is performed during a period in which the required load varies is shown.
  • the height of the graph corresponds to the amount of hydrocarbon supplied per time, and the higher the graph, the larger the amount of hydrocarbon supplied per time.
  • the active NO retained by the exhaust purification catalyst X Quantity and NO X The hydrocarbon supply cycle and the hydrocarbon supply amount are set based on the holdable speed.
  • the amount of particulate matter deposited on the particulate filter has reached a predetermined determination value. For this reason, temperature rise control is started from time t1 in order to regenerate the particulate filter.
  • the hydrocarbon supply interval and the amount of hydrocarbon supply per time are set, and the hydrocarbon is supplied a plurality of times.
  • the temperature increase control shown in FIG. 28 is performed at predetermined time intervals.
  • the operation state of the internal combustion engine is the first operation state.
  • the operating state of the internal combustion engine changes from the first operating state to the second operating state at time t3 during the period in which the temperature raising control is performed.
  • the hydrocarbon supply cycle and the amount of hydrocarbon supply per time are newly calculated and set. For this reason, the hydrocarbon supply cycle and the amount of hydrocarbon supply per change are changing.
  • the operating state of the internal combustion engine changes from the second operating state to the third operating state. For this reason, the supply cycle of hydrocarbons and the supply amount of hydrocarbons are further changed. Thereafter, at time t2, the temperature of the particulate filter reaches the target temperature.
  • the temperature rise control in the operation example the operating state of the internal combustion engine is detected at predetermined intervals, and the amount of hydrocarbons supplied and the amount of hydrocarbons supplied per time are determined based on the detected operating state of the internal combustion engine. The cycle is set. The total supply amount of hydrocarbons is set based on the temperature of the particulate filter detected at each time and the target temperature.
  • the total supply amount of hydrocarbons calculated in the temperature raising control is equivalent to the supply amount of remaining hydrocarbons for raising the temperature of the particulate filter to the target temperature. For this reason, the higher the temperature of the particulate filter, the smaller the total supply amount of hydrocarbons. Further, based on the detected operating state of the internal combustion engine, the hydrocarbon supply cycle and the hydrocarbon supply amount per time are set, and the hydrocarbon supply cycle and the hydrocarbon supply amount per time are changed. ing.
  • the predetermined interval for repeating the setting of the supply interval and the supply amount is not limited to the time interval, and for example, any interval such as the number of times of supplying hydrocarbons can be adopted.
  • similar temperature rise control is continued even after the temperature of the particulate filter reaches the target temperature at time t2. By continuing the temperature rise control, the temperature of the particulate filter can be maintained at the target temperature.
  • the temperature increase control shown in FIG. 28 by repeating the temperature increase control shown in FIG. 28 at predetermined intervals, hydrocarbons are supplied when the temperature of the particulate filter becomes lower than the target temperature, and the particulates
  • the temperature of the curate filter can be maintained at the target temperature. Note that the difference between the temperature of the particulate filter and the target temperature may be small, and the total amount of hydrocarbons supplied may be small. NO due to low total hydrocarbon supply X If the purification rate cannot be kept high, control may be performed to wait for the supply of hydrocarbons until the particulate filter is lowered to a predetermined temperature. Further, the control for maintaining the temperature after the temperature of the particulate filter reaches the target temperature is not limited to this form, and any control can be adopted.
  • FIG. 32 shows another example of operation of the exhaust emission control device in the present embodiment.
  • the operation example shown in FIG. 32 can be applied to an internal combustion engine in which the required load and the like are constant and the operation state is substantially constant.
  • the present invention can be applied to an internal combustion engine in which the operating state has a substantially constant period.
  • the internal combustion engine can be employed during a driving state such as constant speed running of a vehicle with a substantially constant required load.
  • Normal operation is performed until time t1.
  • temperature rise control is started to regenerate the particulate filter.
  • a hydrocarbon supply cycle and a hydrocarbon supply amount per time are set.
  • the hydrocarbon supply is continued a plurality of times at the set hydrocarbon supply cycle and the amount of hydrocarbon supply per time.
  • the temperature of the particulate filter has reached the target temperature.
  • FIG. 33 illustrates still another example of operation of the exhaust emission control device in the present embodiment.
  • the control is switched from the normal operation control to the temperature increase control.
  • additional hydrocarbons are supplied while continuing normal operation control. The supply period of the additional hydrocarbon and the supply amount of the additional hydrocarbon can be determined in advance. At time t1, regeneration of the particulate filter is started.
  • a predetermined amount of hydrocarbon supply FO is performed.
  • the additional hydrocarbon supply FO is performed at predetermined time intervals.
  • An additional hydrocarbon supply FO is performed between the hydrocarbon supply FNs in normal operation.
  • the temperature of the particulate filter has reached the target temperature.
  • the temperature of the exhaust purification catalyst can be raised while suppressing the passage of hydrocarbons in the exhaust purification catalyst.
  • NO held by the exhaust purification catalyst X Quantity and NO X Estimated holding speed of NO, estimated NO X Quantity and NO X
  • the hydrocarbon supply cycle and the amount of hydrocarbon supply per time are set based on the holdable speed
  • the hydrocarbon supply period and the amount of hydrocarbon supply per time may be set based on the fuel injection amount in the combustion chamber and the engine speed.
  • a particulate filter has been described as an example of the post-processing device disposed downstream of the exhaust purification catalyst.
  • the post-processing device is not limited to this mode and is determined in advance.
  • a hydrocarbon supply valve is arranged in the engine exhaust passage, and hydrocarbons are supplied from the hydrocarbon supply valve to supply hydrocarbons to the exhaust purification catalyst.
  • the hydrocarbons can be supplied to the exhaust purification catalyst by any device or control. Note that the above-described embodiments can be appropriately combined. In addition, the order of the steps of the above-described operation control can be appropriately changed as long as the respective operations and functions can be maintained. In each of the above drawings, the same or similar parts are denoted by the same reference numerals. In addition, said embodiment is an illustration and does not limit invention. In the embodiment, the change shown in a claim is included.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)
  • Catalysts (AREA)
  • Filtering Of Dispersed Particles In Gases (AREA)
PCT/JP2011/070086 2011-08-29 2011-08-29 内燃機関の排気浄化装置 WO2013031028A1 (ja)

Priority Applications (5)

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JP2012504214A JP5218698B1 (ja) 2011-08-29 2011-08-29 内燃機関の排気浄化装置
EP11838998.0A EP2589769B1 (de) 2011-08-29 2011-08-29 Abgasreinigungssystem für einen verbrennungsmotor
CN201180004306.9A CN103097680B (zh) 2011-08-29 2011-08-29 内燃机的排气净化装置
US13/510,156 US8689546B2 (en) 2011-08-29 2011-08-29 Exhaust purification system of internal combustion engine
PCT/JP2011/070086 WO2013031028A1 (ja) 2011-08-29 2011-08-29 内燃機関の排気浄化装置

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US20130047588A1 (en) 2013-02-28
EP2589769B1 (de) 2016-03-16
EP2589769A8 (de) 2013-06-26
EP2589769A1 (de) 2013-05-08
JP5218698B1 (ja) 2013-06-26
CN103097680B (zh) 2015-03-11
CN103097680A (zh) 2013-05-08
US8689546B2 (en) 2014-04-08
JPWO2013031028A1 (ja) 2015-03-23
EP2589769A4 (de) 2014-04-30

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